Overlaying ultrasonographic images on direct vision.

Abstract

The objective of this technical advance is to permit in situ visualization of ultrasonographic images so that direct hand-eye coordination can be used during invasive procedures. A method is presented that merges the visual outer surface of a patient with a simultaneous ultrasonographic scan of the patient's interior. The method combines a flat-panel monitor with a half-silvered mirror such that the image on the monitor is reflected precisely at the proper location within the patient. The ultrasonographic image is superimposed in real time on the patient, merging with the operator's hands and any invasive tools in the field of view. Instead of looking away from the patient at an ultrasonographic monitor, the operator sees through skin and underlying tissue as if it were translucent. Two working prototypes have been constructed, demonstrating independence of viewer location and requiring no special apparatus to be worn by the operator. This method could enable needles and scalpels to be manipulated with direct hand-eye coordination under ultrasonographic guidance. Invasive tools would be visible up to where they enter the skin, permitting natural visual extrapolation into the ultrasonographic slice. Biopsy needles would no longer be restricted to lie in the plane of the ultrasonographic scan but could instead intersect it. These advances could lead to increased safety, ease, and reliability in certain invasive procedures.

Image Overlay Guidance for Needle Insertion in CT Scanner

“…In the pursuit of simpler image overlay systems, our group [9], [10] and concurrently Stetten et al [13] investigated 2D image reflection produced in a semitransparent mirror. This technique provides an optically stable 2D reflection image without auxiliary tracking, requiring only a simple preoperative alignment.…”

Laser Needle Guide for the Sonic Flashlight

“…Real-Time Tomographic Reflection (RTTR) was separately proposed by Stetten et al [8], [9], [10], [11] and Masamune et al [12]. Stetten's RTTR system was developed for real-time visualization of ultrasound.…”

Carotid Artery and Jugular Vein Tracking and Differentiation Using Spatiotemporal Analysis

“…We expect this system to be used in conjunction with a new method of ultrasound display, the Sonic Flashlight [9], which employs a half-silvered mirror to project the image directly within the patient. By analyzing the properties of the tracked objects, it should be possible to automatically classify and graphically mark each as an artery, vein, or other tissue type.…”